In addition, when referencing the atr annotations of this database,
please acknowledge their creators (MEDICALgorithmics Ltd, Warsaw, Poland;
efforts coordinated by Michal Tadeusiak).

This database includes 84 long-term ECG recordings of subjects with
paroxysmal or sustained atrial fibrillation (AF). Each record
contains two simultaneously recorded ECG signals digitized at 128 Hz
with 12-bit resolution over a 20 mV range; record durations vary but
are typically 24 to 25 hours.

Two sets of annotations are available here:

The qrs annotations were produced by an automated
QRS detector; in these annotation files, all detected beats (including
occasional ventricular ectopic beats) are labelled N, detected artifacts
are labelled '|', and AF terminations are labelled T.

The atr annotations were obtained by manual
review of the output of an automated ECG analysis system (see
below); in these annotation files, all detected beats are
labelled by type, and rhythm changes are also annotated (see
the summary tables for details).

The AF Termination Challenge Database
consists of 80 one-minute excerpts of a subset of these records (those
numbered 00 through 75). As a guide to selecting the excerpts, “T” were inserted manually in the qrs annotation
files of this subset of the records, to mark spontaneous terminations
of AF episodes with durations of at least one minute.

The original recordings were collected and contributed to PhysioNet by
Steven Swiryn and his colleagues at Northwestern University. They
were digitized and automatically annotated at Boston’s Beth Israel
Deaconess Medical Center. Steven Swiryn and George Moody annotated
the AF terminations.

The atr annotations were developed on PhysioNetWorks and
contributed to PhysioNet by MEDICALgorithmics Ltd (Warsaw, Poland).
The recordings have been automatically annotated using
MEDICALgorithmics’ PocketECG system algorithm (FDA 510(k): K112921)
and manually verified by an experienced team of MEDICALgorithmics' ECG
technicians. The reference annotation development project was
coordinated by Michal Tadeusiak.

Thanks to Mariano Llamedo Soria for reporting an error in the original version
of 20.hea, and for providing a correction incorporated in the current version.